Method of Manufacturing and Assembling Low-Profile Door Frame Corner Posts

The present invention relates to door frames for ground transportation vehicles such as semi-trailers. More particularly, the present invention is directed to a method of manufacturing and assembling a low-profile corner post for the door frame of a semi-trailer.

Enclosed ground transportation vehicles, such as, for example, semi-trailers, box trailers, and box trucks, are one of the most commonly used methods for transporting goods (commonly referred to as “cargo” or “freight”) including, for example, goods stored on pallets and oversized goods such as, for example, equipment and building materials. An enclosed ground transportation vehicle, such as an enclosed semi-trailer, typically includes a frame having axles mounted thereto and wheels rotatably mounted on the axles, a floor platform supported above the frame, side walls extending one on either side of the floor platform, and a roof supported by the side walls vertically above the floor platform. The trailing end of the trailer is enclosed by a pair of doors which are pivotably mounted on and supported by a door frame. The roof, walls, and doors form a barrier around the cargo storage space and protect the cargo stored therein from the wind, rain, debris, etc. and the doors provide access for loading and unloading cargo from the trailer.

The door frame of a semi-trailer includes a horizontal sill member, a pair of vertical corner posts, and a horizontal head member. The horizontal sill member is secured to the frame of the trailer and forms the bottom end of the door frame. The vertical corner posts extend upwardly from opposite ends of the horizontal sill member and are configured to engage hinge plates which are used to pivotably mount the doors to the door frame. The vertical corner posts are also secured to the side walls of the trailer. The horizontal head member extends between the upper ends of the vertical corner posts and is secured to the corner posts and the trailer roof. In addition to supporting the doors, the door frame provides structural support for the side walls and roof to prevent them from collapsing from the dynamic forces experienced during operation of the semi-trailer. Accordingly, the sill member, corner posts, and head member must be sufficiently robust to ensure the door frame is able to resist the forces experienced by the trailer.

In use, the width of the door frame opening (i.e., the distance between the two corner posts) impacts the efficiency of loading and unloading the trailer and the maximum size of goods which can be transported on the trailer. For example, most U.S. states restrict the total width of a semi-trailer to a maximum of 102 ″. Traditional corner posts are generally more than 2 ″ wide. As such, the width of a traditional door frame opening (i.e., the distance between the two corner posts) is typically less than 98″.

As mentioned above, semi-trailers are commonly used for transporting cargo including goods stored on pallets and oversized goods such as equipment and building materials. With respect to palleted goods, pallets are typically constructed in standard sizes with the most common size being 48 ″ long and 40 ″ wide. Goods stored on such pallets are typically packaged to fit within the 48 ″×40 ″ footprint of the pallet, however it is also common for palleted goods to protrude a few inches on either side of the pallet depending on the size, shape, and organization of the goods. When palleted goods are loaded onto a semi-trailer, they are typically organized into two side-by-side rows having a total width of up to 100 ″ or so.

For loading and unloading efficiency purposes, palleted goods are preferably loaded in side-by-side pairs using powered loading equipment, such as, for example, a double pallet forklift, or an automated loading system, such as, for example, an automated conveyor system. However, as should now be appreciated, if the palleted goods protrude on either side of the pallets, the total width of the side-by-side pair of pallets may be greater than width of a traditional door frame opening which would require the pallets to be loaded and unloaded individually; thus, reducing efficiency.

Similarly, oversized goods, such as, for example, equipment and building materials, may have a width greater than 98 ″. Such goods would not fit through a 98 ″ wide traditional door frame opening, and so, would not be transportable using a traditional semi-trailer.

Accordingly, there exists a need for an improved, low-profile corner post which is thin enough such that cargo having a width of up to 100 ″ fits through the door frame opening while simultaneously being robust enough to resist the dynamic forces experienced by the trailer.

In one form thereof, the present invention is directed to a method of manufacturing a corner post of a trailer door frame. The corner post comprises an exterior panel, a U-shaped intermediate panel, an S-shaped extension panel, and a U-shaped interior panel. The exterior panel can be configured to couple a door to the door frame. The U-shaped intermediate panel includes a first planar middle section and first and second leg sections. The first and second leg sections extend from opposite ends of the first planar middle section. The S-shaped extension panel includes a first planar end section, a first S-shaped middle section, and a second planar end section. The first and second planar end sections extend from opposite ends of the first S-shaped middle section. The U-shaped interior panel includes a second planar middle section and third and fourth leg sections. The third and fourth leg sections extend from opposite edges of the second planar middle section.

The method of manufacturing the corner post comprises the steps of: (i) securing the first and second leg sections to the planar panel; (ii) securing the first planar end section of the S-shaped panel to one of the first and second leg sections and/or to the exterior panel; (iii) securing the third leg section of the U-shaped interior panel to the exterior panel; and (iv) securing the fourth leg section of the U-shaped interior panel to the first planar end section of the S-shaped panel and/or to the exterior panel. Preferably, the panels are secured together by welding.

Preferably, the first planar end section of the S-shaped panel includes a first vertical edge having a first plurality of notches formed therein. During assembly, the first vertical edge is disposed adjacent to the second leg section of the first U-shaped panel and the first planar end section is welded to the second leg section and the outer panel interior surface along the first vertical edge.

Preferably, the exterior panel includes a second vertical edge having a second plurality of notches formed therein. During assembly, the second vertical edge is disposed adjacent to the first planar end section and the exterior panel is welded to the first planar end section along the second vertical edge.

Preferably, the second planar middle section of the U-shaped interior panel includes a plurality of slots formed therein. During assembly, the second planar middle section is disposed adjacent to the first planar middle section and the second planar middle section is welded to the first planar middle section along an edge of each slot.

Preferably, the first plurality of notches, the second plurality of notches, and the plurality of slots are substantially filled in with a weld filler material during assembly of the corner post.

Preferably, the method further includes the step of manufacturing the exterior panel, U-shaped intermediate panel, S-shaped panel, and U-shaped interior panel by extruding, bending, stamping, or laser cutting from a stock material. Yet more preferably, the method includes the steps of manufacturing the exterior panel and S-shaped panel by cutting and bending from stock sheets of steel and manufacturing the U-shaped intermediate panel and U-shaped interior panel by laser cutting sections from lengths of rectangular steel tubing stock.

Corresponding reference characters indicate corresponding parts throughout several views. Although the exemplification set out herein illustrates certain embodiments of the invention, the embodiments disclosed below are not intended to be exhaustive or to be construed as limiting the scope of the invention to the precise form disclosed.

1 7 FIGS.- 10 10 12 14 14 16 18 20 22 16 24 22 26 24 22 14 12 10 Referring initially to, a door frame constructed in accordance with the principles of the present invention is designated by the numeral. The door frameis configured to pivotably couple a pair of doorsto a ground transport vehicle, such as, for example an enclosed semi-trailer. A semi-trailertypically includes a framehaving axlesmounted thereto and wheelsrotatably mounted on the axles, a floor platformsupported on top of the frame, side wallsextending one on either side of the floor platform, and a roofsupported by the side wallsvertically above the floor platform. The trailing end of the semi-traileris enclosed by a pair of doorswhich are supported by and pivotably mounted to a door frame.

3 4 FIGS.and 10 28 30 32 28 16 10 32 28 24 30 32 28 34 28 32 30 12 32 36 12 10 24 26 14 As best seen in, the door frameincludes a horizontal sill member, a horizontal head member, and a pair of vertical corner posts. The horizontal sill memberis mounted to the trailer frameand forms the bottom of the door frame. The corner postsextend upwardly one from either end of the horizontal sill memberand couple to the trailer side walls. The horizontal head memberis coupled to and extends between the upper ends of the corner postsvertically above the horizontal sill member. A door frame openingis defined between the horizontal sill member, the corner posts, and the horizontal head member. The trailer doorsare pivotably coupled to the corner postsby hinge plates. In addition to supporting the doors, the door framealso provides structural support for the side wallsand roofof the semi-trailer.

14 38 40 38 40 38 40 40 38 4 6 FIGS.- 5 FIG.B 5 FIG.B 5 FIG.B Semi-trailersare commonly used for transporting cargostored on pallets() and oversized cargo such as equipment and building materials (not shown). With respect to palleted cargo, palletsare typically constructed in standard sizes with the most common size being 48 ″ long (, dimension line L) and 40 ″ wide (dimension line W). The cargostored on such 48 ″×40 ″ pallets may protrude slightly on either side of the palletwhereby the total width of a palletof cargo(, dimension line CW) can be approximately 50″.

40 38 38 24 38 14 14 40 38 6 FIG. When palletsof cargoare loaded onto a semi-trailer, they are typically organized into two side-by-side rows having total width (, dimension line TCW) of up to 100 ″ or so. This ensures there is a small amount of space between the pallets/cargoand the trailer side wallsfor maneuvering the pallets/cargowithin the trailerwhile minimizing the amount of empty space within the trailer. For loading and unloading efficiency purposes, palletsof cargoare preferably loaded in side-by-side pairs using powered loading equipment, such as, for example, a double pallet forklift, or an automated loading system, such as, for example, an automated conveyor system.

10 32 34 40 38 34 14 34 32 32 30 14 6 FIG. 6 FIG. 7 FIG.B In the present invention, the door frame, and, more particularly, the corner posts, are configured such that the width of the door frame opening(, dimension line DFW) is approximately 100 ″ whereby two side-by-side palletsof cargohaving a total width TCW of up to 100 ″, or oversized cargo having a width of up to 100 ″, can be loaded through the door frame opening. In this regard, most U.S. states restrict the total width of a semi-trailer(, dimension line TW) to a maximum of 102 ″ wide. To ensure the door frame openingis approximately 100 ″ wide, the corner postsshould have a thickness T () of approximately 1 ″. However, the corner postsmust also maintain the structural strength necessary to support the horizontal head memberand resist the dynamic experienced during operation of the semi-trailer.

32 32 32 42 44 46 48 7 14 FIGS.B- To minimize the thickness T of the corner postswhile maintaining the structural strength thereof, the corner postsare constructed from a plurality of layered panels which are secured together to form a rectangular box-shaped structure. Specifically, as best seen in, the corner postsare constructed from a plurality of panels including an exterior panel, a U-shaped intermediate panel, an S-shaped extension panel, and a U-shaped interior panel.

42 32 50 52 50 42 42 42 42 42 42 52 50 42 36 12 32 a b b 7 FIG.A-B The exterior panelforms the outermost portion of the corner postand includes a planar sectionand an angled section. The planar sectionextends from a first endof the exterior paneltowards a second endof the exterior paneland is defined between a planar interior surfaceIS and a planar exterior surfaceES. The angled sectionextends from the end of the planar sectionto the exterior panel second endand is adapted to engage hinge plates() for coupling a doorto the corner post.

44 50 54 56 56 54 54 42 56 56 54 56 56 42 a b a b a b The U-shaped intermediate panelis adapted to be secured to the exterior panel planar sectionand includes a first planar middle sectionand a pair of leg sections,extending one from each end of the first planar middle section. The first planar middle sectionextends preferably parallel to the exterior panel interior surfaceIS. The leg sections,are preferably the same length and extend parallel to each other and perpendicularly from the first planar middle section. During assembly, the leg sections,are placed against/abutting secured the exterior panel interior surfaceIS and are secured thereto.

46 42 44 24 46 46 46 58 58 60 58 46 46 62 62 24 46 32 a b a b a a b The S-shaped extension panelis secured to the exterior panel interior surfaceIS adjacent to the U-shaped intermediate paneland secures to the trailer side wallsby, for example, welding, brazing, adhering, or fastening. The S-shaped extension panelincludes a first end, a second end, a pair of planar end sections,, and an S-shaped middle section. The first planar end sectionextends from the extension panel first endtowards the extension panel second endand can include a plurality of bores. The boresare adapted to receive fasteners (not shown) for securing the trailer side wallsto the S-shaped extension panels, and, hence, to the corner posts.

58 46 46 58 58 58 14 60 58 58 58 42 56 b b a a b a a b a b. 7 FIG.B The second planar end sectionextends from the extension panel second endtowards the extension panel first endparallel to the first planar end section. As best seen in, the second planar end sectionis preferably offset horizontally from the first planar end sectiontowards the interior of the trailer. The S-shaped middle sectionextends between and connects the first and second planar end sections,. During assembly, the first planar end sectionplaced against/abutting the exterior panel inner surfaceIS adjacent to the U-shaped intermediate panel second leg section

58 42 56 58 58 46 64 46 58 64 a b a v a n a v n 8 10 FIGS.- 8 10 FIGS.- Preferably, the first planar end sectionis secured to both the exterior panel inner surfaceIS and the second leg section. Specifically, as best seen in, the first planar end sectionpreferably includes a vertical edgelocated at the extension panel first endand a plurality of regularly spaced mounting notchesextending into the extension panel first endalong the vertical edge. The mounting notchescan be trapezoid-shaped notches (as shown in), or any other shape as may be necessary or desirable.

46 58 42 58 56 46 42 56 64 64 66 56 42 64 a v b b e n c b n During assembly, the S-shaped extension panelis positioned with the first planar end sectionagainst/abutting the exterior panel interior surfaceIS and the vertical edgeagainst/abutting the second leg section. The S-shaped extension panelis then secured to the exterior paneland the U-shaped intermediate panel leg sectionby welding along the edgesof each mounting notchand along corner edgeformed between the second leg sectionand the exterior panel interior surfaceIS. Preferably, a filler material is used during the welding process whereby the notchesare substantially filled by the weld filler material (not shown).

11 12 FIGS.and 42 42 42 42 68 42 42 42 46 42 68 68 68 a v a n a v v e n n Yet more preferably, as best seen in, the exterior panelfirst endincludes a vertical edgelocated at the exterior panel first endand a plurality of regularly spaced mounting notchesextending into the exterior panel first endalong the vertical edge. During assembly, the exterior paneland the S-shaped extension panelare further secured together by welding along the exterior panel vertical edgeand along the edgesof the exterior panel mounting notches. Preferably, the exterior panel notchesare also filled by the weld filler material (not shown).

7 FIG.B 6 FIG. 48 44 32 34 48 32 48 70 72 72 70 70 54 72 42 72 58 72 72 42 58 c d c d a c d a Returning to, the U-shaped interior panelis secured over top of the U-shaped intermediate paneland forms the innermost portion of the corner posts. The total width of the door frame opening(, dimension line DFW) is defined between the U-shaped interior panelsof the two vertical corner posts. The U-shaped interior panelincludes a second planar middle sectionand a pair of leg sections,extending one from each end of the second planar middle section. During assembly, the second planar middle sectionis placed against/abutting the first planar middle sectionwith the interior panel leg sectionabutting the exterior panel interior surfaceIS and the interior panel leg sectionabutting the first planar end section. The interior panel leg sections,are then secured the exterior panel interior surfaceIS and the first planar end section, respectively.

70 74 70 54 74 74 64 68 74 s e s n n s Preferably, the second planar middle sectionincludes a plurality of oval-shaped slots. During assembly, the second planar middle sectionis secured first planar middle sectionby welding along the edgesof the oval-shaped slots. Preferably, like the extension panel mounting notchesand the exterior panel mounting notches, the oval-shaped slotsare also substantially filled by the weld filler material (not shown).

8 FIG. 11 12 FIGS.and 72 76 76 58 42 76 42 72 58 42 68 68 76 42 46 42 68 68 42 76 d a d a n n v e n Preferably, as best seen in, interior panel leg sectionincludes an extended portion. The extended portionextends vertically above the first planar end sectionand abuts against the exterior panel interior surfaceIS. During assembly, the extended portioncan be welded to the exterior panel interior surfaceIS for securing the interior panel leg sectionto both the first planar end sectionand the exterior panel. Additionally, as best seen in, the exterior panel notchescan be configured such that at least one exterior panel notchis located adjacent to the extended portion. As such, when the exterior panelis welded to the S-shaped extension panelalong the exterior panel vertical edgeand along the edgesof the exterior panel mounting notches, the exterior panelis also welded to the extended portion.

32 42 44 46 48 42 44 46 48 44 48 68 64 74 42 46 48 n n s With respect to manufacturing and assembling the corner posts, each of the panels,,,can be manufactured by, for example, extruding, bending, or otherwise molding or forming from a high-strength metal, such as, for example, steel or aluminum. Preferably, each of the panels,,,can be manufactured by cutting sections from stock sheets of steel and bending the steel sheet sections into the desired shapes. The U-shaped intermediate paneland the U-shaped interior panelcan also be manufactured by laser cutting sections from lengths of rectangular steel tubing stock. Preferably, the exterior panel mounting notches, the extension panel mounting notches, and the oval-shaped slotscan be formed in the panels,,by, for example, laser cutting, plasma cutting, waterjet cutting, oxy-fuel gas cutting, or stamping or press cutting.

42 44 46 48 32 44 42 56 56 42 44 42 56 56 42 44 42 46 44 58 42 58 56 46 42 58 42 a b a b a v b a Once the panels,,,have been manufactured, the corner postscan then be assembled by, for example, positioning the U-shaped intermediate paneladjacent to the exterior panelwith the intermediate panel leg sections,against/abutting the exterior panel interior surfaceIS. The U-shaped intermediate panelis then temporarily secured to the exterior panelby tack welding the intermediate panel leg sections,to the exterior panel interior surfaceIS. After the U-shaped intermediate panelis temporarily secured to the exterior panel, the S-shaped extension panelis positioned adjacent to the U-shaped intermediate panelwith the first planar end sectionagainst/abutting the exterior panel interior surfaceIS and the extension panel vertical edgeagainst/abutting the intermediate panel leg section. The S-shaped extension panelis then temporarily secured to the exterior panelby tack welding the first planar end sectionto the exterior panel interior surfaceIS.

46 42 44 46 44 42 56 42 46 44 58 42 56 58 66 56 42 64 64 a a b v c b e n. After the S-shaped extension panelis temporarily secured to the exterior panel, if both the U-shaped intermediate paneland the S-shaped extension panelare located in the desired position, the U-shaped intermediate panelis permanently secured to the exterior panelby welding the intermediate panel leg sectionto the exterior panel interior surfaceIS. The S-shaped extension panelis then permanently secured to the exterior panel and the U-shaped intermediate panelby welding the first planar end sectionto the exterior panel interior surfaceIS and the intermediate panel leg sectionalong the extension panel vertical edge, the corner edgesbetween the intermediate panel leg sectionand the exterior panel interior surfaceIS, and the edgesof the extension panel mounting notches

44 46 42 48 44 56 42 70 54 56 58 48 42 44 46 56 42 56 58 70 54 74 74 42 58 76 42 68 68 a b a a b a e s a v e n. After the U-shaped intermediate paneland the S-shaped extension panelare permanently secured to the exterior panel, the U-shaped interior panelis positioned adjacent to the U-shaped intermediate panelwith the interior panel leg sectionagainst/abutting the exterior panel interior surfaceIS, the second planar middle sectionagainst/abutting the first planar middle section, and the interior panel leg sectionagainst/abutting the first planar end section. The U-shaped interior panelis then permanently secured to the exterior panel, the U-shaped intermediate panel, and the S-shaped extension panelby welding the interior panel leg sectionto the exterior panel interior surfaceIS, welding the interior panel leg sectionto the first planar end section, and welding the second planar middle sectionto the first planar middle sectionalong the edgesof the oval-shaped slots. Additionally, the exterior panelis permanently secured to the first planar end sectionand the extended portionby welding along the exterior panel vertical edgeand along the edgesof the exterior panel mounting notches

32 While this invention has been described as having an exemplary embodiment, the present invention may be further modified within the spirit and scope of this disclosure, such as, for example, by re-ordering the steps for manufacturing and assembling the corner posts. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles.